1. Field of the Invention
The present invention relates generally to manufacturing technology of photovoltaic devices, and more particularly, to a rapid temperature process (RTP) heating system and an RTP heating method.
2. Description of the Related Art
The existing photovoltaic devices are usually made by that a Mo layer is disposed on a glass substrate and a light absorption layer, e.g. copper indium gallium selenide (CIGS) layer or copper indium selenide (CIS) layer, is produced on the Mo layer. When it is intended to produce the light absorption layer, the temperature needs to be heightened up to 500° C. and higher, and then the light absorption layer can be formed on the Mo layer by sputtering, vapor deposition, electroplating, or inkjet.
In the process of production of the above-mentioned light absorption layer, the method of heightening the temperature includes the popular RTP is to heat photovoltaic devices by a thermal source located above the photovoltaic devices. The thermal source can be a resistance-type heating wire or an infrared heater for heating the upper surface of the photovoltaic devices.
In the Paragraph [0013] of the specification of the U.S. Pat. Pub. No. 2008/0305247, it mentioned that German Pat. No. 19936081A1 disclosed a conventional RTP for manufacturing a CIS or CIGS layer.
U.S. Pat. Pub. No, 2009/0305455 disclosed an RTP which is to heat the upper and lower surfaces of the photovoltaic devices by an infrared lamp under the temperature of 200-600° C. However, the photovoltaic devices are made of aluminum rather than glass.
When the light absorption layer is manufactured by the RTP, if the substrate is made of glass, there will be a problem. For example, when the light absorption (CIGS) layer is manufactured, the optimal temperature is 500° C. and higher and the deformation temperature of the glass is 510° C. or so, such that the glass substrate below the CIGS layer will be softened for deformation and the whole photovoltaic devices will become unusable due to such deformation. Perhaps, that may be why the substrate is made of aluminum in the U.S. Pat. Pub. No, 2009/0305455.
As can be seen from the above, in the existing temperature control technology, it is very difficult so far to integrate the manufacturing temperature (500° C. and higher) of the light absorption layer and the deformation temperature (510° C.) of the glass on the glass substrate to allow the light absorption layer to be manufactured on the glass.